PERMANENT FLOOD BARRIER: RETRACTABLE BARRIERS
INSIDE THE FLOODPLAIN

What Is It?

Cost: Dependent on building site. See project examples below for project costs.
Applications: Can be retrofitted to existing sites. Costs will likely be lower for new construction, as siting considerations can be built into design costs.
Service Life: Barriers themselves have extensive service life (~50+ years). Seals may require replacement every 10 years, depending on model.

Temporary flood barriers are effective, but require time and labor to deploy. Depending on site conditions and frequency of flooding, it may be more cost effective in the long-term to install a permanent, in-situ flood barrier. There are many permanent flood barrier options that are passive, are recessed into a site, and require no deployment. In some cases, hydrostatic pressure from rising floodwaters causes flood barriers to rise from a recessed location until the barrier is fully upright and automatically sealed. Some products (e.g. Aquafragma) will issue warnings before deployment occurs. Other permanent barriers require human intervention, but often have shorter deployment times than temporary barriers.

Permanent barriers will easily deploy and retract until end of service life with less setup and cleanup required than temporary barriers. Retractable permanent barriers can be combined with other permanent flood barriers (e.g. flood walls). The retractable barriers can be installed in gaps and entrances in the flood walls to allow for building access and mobility until rising floodwaters necessitate deployment of the retractable barrier.

Regular maintenance will be necessary to ensure the barrier is ready for deployment when a flood occurs, though maintenance will vary depending on the type of barrier installed. As permanent retractable barriers are often recessed into the ground until deployment, installation in existing sites will require construction and excavation. Non-passive barriers will typically require shallower foundations, lowering excavation costs. Consulting an engineer to determine optimal siting and certify structural integrity should also be considered. Some suppliers (e.g. FloodBreak) include engineer certification in every purchase.

Benefits

  • Passive barriers minimize human intervention in many areas, including deployment, demounting, and storage, as well as needs for training personnel. Permanent barriers that are not passive often still have lower deployment times and human intervention needs to deploy.
  • Passive barriers do not use electricity, allowing for constant flood protection.
  • Passive barriers do not need to be deployed ahead of a flood event. This provides protection against flash floods while also allowing site access until flood waters reach the building site.
  • Passive barriers are installed onsite and are typically custom sized for the site’s needs.
  • Recessed permanent barriers can be modified to minimize disruption to building aesthetics.
  • Passive barriers are preferred by FEMA as a best management practice for flood mitigation.

Drawbacks

  • Onsite construction and excavation are usually needed to install permanent barriers.
  • Upfront costs, especially for barriers requiring onsite construction, will be significantly higher than temporary barriers and flood shields.
  • Due to higher costs, passive barriers usually need to be combined with other site protection (e.g. flood walls) to maximize effectiveness for larger sites.

Regulatory Impacts and Requirements

A summary of regulatory touchpoints follows below:
retractable-barriers

Financing Options, Incentives, And Rebates

Additional Resources

Project Examples

  • Lourdes Hospital, NY: 11 FloodBreak passive floodgates combined with 11-foot floodwall at a cost of approx. $7 million
  • Route 22 Honda, NJ: Single FloodBreak passive floodgate installed in front of underground garage showroom entrance. Successful deployment and protection in two flood events resulted in reduction of insurance deductible from $100,000 to $10,000.

SAMPLE OF SUPPLIERS

Lift Out: Stored underground, has to be lifted out when a flood could occur.

Hinged Barrier: Swings into place.

Sliding Barrier: Stored above or beside an opening and slides into place.

SOURCES

Photo credits: Labeled for reuse by NJmonthly.com